Quote:
Originally posted by YogsVR4
hp/l means little to nothing in the actual performance of the engine.
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Actualy it can be a good indication of how highly tuned the engine is, and therefore how well it behaves at low or high rpm.
Generaly the more hp/L and engine has the less flexiable it will be at low RPM.
It is also a good indication of the engines purpose, is it built for economy, or performance? Or a compromise of the two.
Due to the limitions of useing Cam Shafts to control air flow into and out of an engine it is very hard to make an engine with a high hp/L ratio, and a good flat driveable torque curve.
And so the higher the ratio the closer the engine gets to being usefull for little more than racing.
There are of course exceptions to this:
Engines with variable lift valve set ups like Honda's VTEC allow an engine to have two power curves, one for high rpm and so high hp, and one for low rpm and torque, and so you get a high hp/L engine that is still flexiable.
Engines with variable cam timeing offer a similar advantage.
Engines fitted with forced induction are differnt again. Although a F/I engine with a high hp/l ratio will be less flexiable than one with a low hp/L ratio it will not be as extreme as comparing two Naturaly Asperaited engines.
And of course as enginers learn more, engines get better.
Its possible for an engine design to get a high hp/l ratio over its life time, with out sacrificing any of its flexablity.
The evolution of the LS1 to the LS6 is a good example of this.
Hp/L is also a useful way of comparing the level of technology and complexity in an engine, as well as its efficancy.
Street driveable engines with very high hp/L ratios require more technology, complexity and efficancy to get there. It is a good indication of the engine building skills and attention to detial of a Manufactor.
And finnaly theres bragging rights: Hahaha, my 1.0L 2cyl engine makes more hp than your 5.7L V8 :finger: (if you look at hp/L that is!
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If your looking to buy a car then its a number that I would pay little attention to, although in some cases engines with higher hp/l ratios will be more efficant when driven gently.